H.248 is a protocol recommendation from the ITU Telecommunication Standardization Sector (ITU-T), which enables separation of call control from media conversion. H.248 defines a Media Gateway Controller (MGC) and a Media Gateway (MG), where a given MGC may control more than one (but usually fewer than ten) MGs. During the signaling process, which establishes a call from one endpoint to another endpoint, the MGC assigns the call to one of several MGs. However, some MGs may be more congested than others or may have fewer remaining licensed instances of a desired codec for use in a call.
Most MGCs use a round robin approach to distribute calls and rely on a congestion detection mechanism such as the ones described in the ITU-T Recommendation H.248.10 (Gateway control protocol: Media gateway resource congestion handling package) or ITU-T Recommendation H.248.32 (Gateway control protocol: Detailed congestion reporting package) to redirect traffic when congestion occurs. The round robin approach attempts to ensure fairness by spreading out the received calls one after the other to each available MG. However, the round robin approach can result in unbalanced load because one given call may use more resources than another given call (e.g., by using different codecs). When a particular MG happens to be assigned multiple calls using high levels of resources, congestion may occur. The congestion detection mechanism relies on MGs to request call diversion or call drops from the MGC when congestion occurs. The congestion detection mechanism is reactive, though, and is applied after congestion is present.
Other implementations may use an approach similar to the one described in the ITU-T Recommendation H.248.63 (Gateway control protocol: resource management packages) or in EP 2146467A1. This approach relies entirely on the MGC to reserve and/or allocate media capability (referred to as “abstract resource” in the recommendation) on the MGs it controls, hence requiring the MGC to have a holistic view of the internal limitations inherent to its MGs. The MGs then abide by the restrictions imposed by the MGC. Recommendation H.248.63 does not take into account the impact that using one unit of a given media capability has on the overall performance of a MG. There is a need for a more robust and efficient way to manage MGs.